Faculty Bibliography

PURPOSE/OBJECTIVE:To determine the association between osseous injuries and short-term clinical outcome in patients with anterior cruciate ligament (ACL) tear. MATERIALS AND METHODS/METHODS:The retrospective study was performed with institutional review board approval, and the requirement to obtain informed consent was waived. The study group consisted of 114 patients (57 male and 57 female patients with a mean age of 26.1 and 25.1 years, respectively) with ACL tear who underwent magnetic resonance (MR) imaging and ACL reconstruction surgery and who filled out International Knee Documentation Committee (IKDC) knee evaluation questionnaires before and 1 year after surgery. All MR images were independently reviewed by two radiologists to determine the presence of a cortical depression fracture on each surface of the knee joint. Bone marrow edema volume was quantified by using segmentation software. Correlation coefficients were used to determine the association between bone marrow edema volume and IKDC score. A multivariate analysis model was used to compare IKDC scores in patients without fracture, patients with a single fracture, and patients with multiple fractures. RESULTS:There was no significant association between total bone marrow edema volume and preoperative or postoperative IKDC score (P = .32 and P = .91, respectively). The mean preoperative and postoperative IKDC scores were 53.4 ± 18.6 and 93.0 ± 5.0, respectively, for patients without fracture, 54.8 ± 13.6 and 87.3 ± 10.8 for patients with a single fracture, and 53.1 ± 17.2 and 83.4 ± 12.7 for patients with multiple fractures. Patients with single and multiple fractures had similar (P = .91) preoperative IKDC scores but significantly lower (P < .001) postoperative IKDC scores compared to patients without fracture. CONCLUSION/CONCLUSIONS:Cortical depression fractures in patients with ACL tear are associated with decreased clinical outcome scores 1 year after ACL reconstruction surgery.

OBJECTIVE:To compare the diagnostic performance of FSE-Cube, a three-dimensional isotropic resolution intermediate-weighted fast spin-echo sequence, with a routine magnetic resonance (MR) protocol at 3.0 T for detecting surgically confirmed meniscal tears of the knee joint in a large patient population. METHODS:FSE-Cube was added to a routine MR protocol performed at 3.0 T on 250 patients who underwent subsequent knee arthroscopy. Three radiologists independently used FSE-Cube during one review and the routine MR protocol during a second review to detect medial and lateral meniscal tears. Using arthroscopy as the reference standard, the sensitivity and specificity of FSE-Cube and the routine MR protocol for detecting meniscal tears were determined for all readers combined. McNemar's tests were used to compare diagnostic performance between FSE-Cube and the routine MR protocol. RESULTS:FSE-Cube and the routine MR protocol had similar sensitivity (95.5%/95.3% respectively, P = 0.94) and similar specificity (69.8%/74.0% respectively, P = 0.10) for detecting 156 medial meniscal tears. FSE-Cube had significantly lower sensitivity than the routine MR protocol (79.4%/85.0% respectively, P < 0.05) but similar specificity (83.9%/82.2% respectively, P = 0.37) for detecting 89 lateral mensical tears. For lateral meniscal tears, FSE-Cube had significantly lower sensitivity (P < 0.05) than the routine MR protocol for detecting 19 root tears but similar sensitivity (P = 0.17-1.00) for detecting all other tear locations and types. CONCLUSION/CONCLUSIONS:FSE-Cube had diagnostic performance similar to a routine MR protocol for detecting meniscal tears except for a significantly lower sensitivity for detecting lateral meniscal tears, which was mainly attributed to decreased ability to identify lateral meniscus root tears.

Due to its high spatial resolution and excellent tissue contrast, magnetic resonance imaging (MRI) has become the most commonly used imaging method to evaluate joints. Most musculoskeletal MRI is performed using 2D fast spin-echo sequences. However, 3D sequences have also been used for joint imaging and have the advantage of acquiring thin continuous slices through joints, which reduces the effects of partial volume averaging. With recent advances in MR technology, 3D sequences with isotropic resolution have been developed. These sequences allow high-quality multiplanar reformat images to be obtained following a single acquisition, thereby eliminating the need to repeat sequences with identical tissue contrast in different planes. Preliminary results on the diagnostic performance of 3D isotropic resolution sequences are encouraging. However, additional studies are needed to determine whether these sequences can replace currently used 2D fast spin-echo sequences for providing comprehensive joint assessment in clinical practice.

PURPOSE/OBJECTIVE:To compare the diagnostic performance of iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL)-spoiled gradient-recalled echo (SPGR) with that of standard magnetic resonance (MR) arthrography sequences for detecting and grading cartilage lesions within the hip joint during MR arthrography. MATERIALS AND METHODS/METHODS:Following institutional review board approval, 67 consecutive hip MR arthrograms were retrospectively reviewed independently by three musculoskeletal radiologists and one musculoskeletal fellow. IDEAL-SPGR images and the two-dimensional images, the latter from the routine MR arthrography protocol, were evaluated at separate sittings to grade each articular surface of the hip joint. By using arthroscopy as the reference standard, the sensitivity and specificity of the two techniques for detecting and grading cartilage lesions were determined. The McNemar test was used to compare diagnostic performance. Interreader agreement was calculated using Fleiss κ values. RESULTS:For all readers and surfaces combined, the sensitivity and specificity for detecting cartilage lesions was 74% and 77%, respectively, for IDEAL-SPGR and 70% and 84%, respectively, for the routine MR arthrography protocol. IDEAL-SPGR had similar sensitivity (P = .12) to and significantly lower specificity (P < .001) than the routine MR arthrography protocol for depicting cartilage lesions. When analyzing the differences in sensitivity and specificity by reader, the two readers who had experience with IDEAL-SPGR had no significant difference in sensitivity and specificity for detecting cartilage lesions between the two sequences. For all readers and surfaces combined, IDEAL-SPGR had a higher accuracy in correctly grading cartilage lesion (P = .012-.013). Interobserver agreement for detecting cartilage lesions did not differ between the two techniques. CONCLUSION/CONCLUSIONS:IDEAL-SPGR had similar sensitivity and significantly lower specificity for detecting cartilage lesions and higher accuracy for grading cartilage lesions than did a routine MR arthrography protocol; the lower specificity of IDEAL-SPGR for detecting cartilage lesions was not seen in experienced readers.

Magnetic resonance (MR) imaging plays an integral role in the assessment of articular cartilage. This article discusses the role of MR imaging in the evaluation of articular cartilage, the appearance of cartilage lesions on MR imaging, and the currently available MR imaging techniques for evaluating cartilage morphology. A limitation of currently available sequences is their inability to consistently detect superficial degenerative and posttraumatic cartilage lesions that may progress to more advanced osteoarthritis. In the future, improved image quality may allow for better evaluation of articular cartilage and earlier detection of cartilage lesions.

PURPOSE/OBJECTIVE:To determine whether preoperative magnetic resonance (MR) imaging could help identify factors associated with poor clinical outcome after arthroscopic partial meniscectomy (APM) in middle-aged and elderly patients with meniscal tears. MATERIALS AND METHODS/METHODS:The prospective, institutional review board-approved, HIPAA-compliant study was performed with informed consent in 53 men and 47 women (average ages, 54.5 and 56.6 years, respectively). Patients underwent knee MR imaging before APM; clinical symptoms were evaluated preoperatively and 1 year postoperatively with International Knee Documentation Committee (IKDC) questionnaire. Overall severity of knee joint degeneration and severity of each feature of joint degeneration were assessed with Boston Leads Osteoarthritis Knee (BLOK) scoring system. Tear length was measured, and type of meniscal tear was classified. Spearman correlation coefficients and relative risks showed the relationship between clinical outcome after APM (difference between preoperative and postoperative IKDC scores) and severity of joint degeneration. RESULTS:Seventy-four patients with isolated medial APM had a significant (P < .05) inverse correlation between clinical outcome and severity of cartilage loss and bone marrow edema in the medial femoral condyle and medial tibial plateau. Fifteen patients with isolated lateral APM had a significant (P < .05) inverse correlation between clinical outcome and severity of cartilage loss in the lateral femoral condyle and lateral tibial plateau and bone marrow edema in the lateral femoral condyle. One hundred patients with APM had a significant (P < .05) inverse correlation between clinical outcome and severity of meniscal extrusion, total BLOK score, and meniscal tear length. A significantly (P < .05) increased relative risk that a patient would not definitely improve after APM was observed if a meniscal root tear was present. CONCLUSION/CONCLUSIONS:Poorer clinical outcome after APM was associated with greater severity of cartilage loss and bone marrow edema in the same compartment as the meniscal tear, greater severity of meniscal extrusion, greater overall severity of joint degeneration, a meniscal root tear, and a longer meniscal tear at preoperative MR imaging.

OBJECTIVE:The objective of our study was to determine whether 3D sequences can improve the diagnostic performance of a routine MR protocol for detecting cartilage lesions within the knee joint at 3 T. SUBJECTS AND METHODS/METHODS:An iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) spoiled gradient-recalled echo (SPGR) sequence (n = 75 patients) or an IDEAL gradient-recalled acquisition in a steady state (GRASS) sequence (n = 75 patients) was added to routine 3-T knee MR protocol to examine 150 patients who subsequently underwent arthroscopic knee surgery. Each articular surface of the knee joint was graded at arthroscopy. All MR examinations were independently reviewed twice by two musculoskeletal radiologists. During the first review, the routine MR protocol was used alone to grade each articular surface of the knee joint; during the second review, the routine MR protocol was used with IDEAL-SPGR or IDEAL-GRASS. Using arthroscopy as the reference standard, the sensitivity and specificity for detecting cartilage lesions and the proportion of correctly graded cartilage lesions were determined for the routine MR protocol alone and for the routine MR protocol with IDEAL-SPGR or IDEAL-GRASS. The McNemar test was used to compare sensitivity, specificity, and accuracy values and proportions of correctly graded cartilage lesions. RESULTS:There was a statistically significant improvement in the specificity (p < 0.05) but not the sensitivity (p = 0.08-0.32) for detecting cartilage lesions when using the routine MR protocol with IDEAL-SPGR or IDEAL-GRASS. There was also a statistically significant (p < 0.05) improvement in the proportion of correctly graded cartilage lesions when using the routine MR protocol with IDEAL-SPGR or with IDEAL-GRASS. CONCLUSION/CONCLUSIONS:Adding 3D sequences to a routine MR protocol improves the diagnostic performance for detecting cartilage lesions within the knee joint at 3 T.

PURPOSE/OBJECTIVE:To compare the diagnostic performance of iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) gradient-recalled acquisition in steady-state (GRASS) imaging with a routine magnetic resonance (MR) imaging protocol for evaluating knee cartilage at 3.0 T in patients by using arthroscopy as the reference standard. MATERIALS AND METHODS/METHODS:This prospective Health Insurance Portability and Accountability Act-compliant study was performed with a waiver of informed consent from the institutional review board. IDEAL GRASS was added to routine 3.0-T knee MR protocol performed in 95 symptomatic patients (48 males, mean age, 34.5 years; 47 females, mean age, 35.5 years) who underwent subsequent arthroscopic surgery. Radiologists used the routine MR protocol during the first review and IDEAL GRASS during the second to grade each articular surface and to determine the presence of meniscal tears. By using arthroscopy as the reference standard, the sensitivity, specificity, and accuracy of both imaging methods for detecting cartilage lesions and meniscal tears were determined. RESULTS:By using the z test to compare parameters between methods, the respective sensitivity, specificity, and accuracy for detecting all 192 cartilage lesions were 68.5%, 92.6%, and 84.5% for IDEAL GRASS and 66.1%, 92.9%, and 83.9% for the routine MR protocol. There was no significant difference (P = .34-.83) in parameters between methods for detecting cartilage lesions. The respective parameters for detecting 50 medial meniscal tears were 85.0%, 91.1%, and 87.9% for IDEAL GRASS and 94.0%, 90.0%, and 92.1% for the routine MR protocol. The parameters for detecting 31 lateral meniscal tears were 58.0%, 90.6%, and 80.0% for IDEAL GRASS and 80.1%, 91.4%, and 87.9% for the routine MR protocol. The routine MR protocol had a significantly higher sensitivity for detecting medial meniscal tears (P = .04) and lateral meniscal tears (P = .01) and significantly higher accuracy for detecting lateral meniscal tears (P = .03) than IDEAL GRASS. CONCLUSION/CONCLUSIONS:IDEAL GRASS has similar diagnostic performance as routine MR protocol for evaluating the articular cartilage of the knee in clinical patients at 3.0 T but has significantly lower sensitivity and accuracy for detecting meniscal tears.

Fat/water separation methods such as fluctuating equilibrium magnetic resonance and linear combination steady-state free precession have not yet been successfully implemented at 3.0 T due to extreme limitations on the time available for spatial encoding with the increase in magnetic field strength. We present a method to utilize a three-dimensional radial sequence combined with linear combination steady-state free precession at 3.0 T to take advantage of the increased signal levels over 1.5 T and demonstrate high spatial resolution compared to Cartesian techniques. We exploit information from the two half-echoes within each pulse repetition time to correct the accumulated phase on a point-by-point basis, thereby fully aligning the phase of both half-echoes. The correction provides reduced sensitivity to static field (B(0)) inhomogeneity and robust fat/water separation. Resultant images in the knee joint demonstrate the necessity of such a correction, as well as the increased isotropic spatial resolution attainable at 3.0 T. Results of a clinical study comparing this sequence to conventional joint imaging sequences are included.